This invention relates to mobile storage systems, and in particular to means for driving the mobile storage units of a system along a track set on a building floor.
Mobile storage systems comprise a series of storage units which have shelves or bins, for example. Each of the storage units is movable on tracks to create an access aisle between two of the units and to establish the others in close side-by-side relationship to minimize the amount of floor space required for the units. Especially in larger mobile storage units and systems, the carriages are quite large, and there is no real problem with space within the carriages for drives and drive units. In smaller systems, however, space for these carriages can be a problem, particularly vertical space or headroom within the carriage and below the lowest shelf within the storage unit. Since space was never a problem in the larger units, pillow block bearings were always used to journal the drive shaft and the driven shaft, because of their relative ease of installation. Since space becomes a problem in the smaller units, however, pillow blocks are inappropriate for use in them. An idea of the amount of room required to accommodate the pillow block bearings, including associated attachment means, can be obtained by reference to Peterman, U.S. Pat. No. 4,618,191. Clearly, a different means of journaling the shafts is needed. Also, pillow block bearings can be too expensive for use in lower capacity units.
In addition, a chain drive is one way to reduce the need for headroom in a carriage. Such a drive requires, however, the ability to apply and adjust tension to the drive chain. With access to any tensioner limited, it would be best if the necessity of access were limited, that is, if it were easy to adjust the tension and the tension did not require frequent adjustment.
This invention relates to improvements to the apparatus described above and to solutions to the problems raised thereby.